Minds and Machines spring 2003

Content: psychosemantics

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preliminaries

• papers due in class #23

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“A recipe for thought”•

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Fred Dretske

a sketch of a “naturalistic” account of intentional mental states (a “psychosemantics”) “Thought may be intentional,but that isn’t the property weare seeking a recipe tounderstand. As long as theintentionality we use is not itselfmental, then we are as free to use intentionality in our recipefor making a mind as we are inusing electrical conductors inbuilding an amplifier orgumdrops in making cookies”

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Dretske’s example of “original” (underived) intentionality

the compass indicates (when used properly) the location of the north pole, not the whereabouts of the Three Bears (even if the Three Bears are at the north pole)

• so the way the compass represents seems importantlysimilar to how beliefs represent—one may believe that thelocation of the pole is over there and not believe that thelocation of the Three Bears is over there (even if the ThreeBears are at the north pole)

• see “Intentionality” on intentionality/intensionality 4

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“Intentional systems, then, are not the problem. They can be picked up for a few dollars at your local hardware store.”

But:

“We are…trying to build systems that exhibit what Chisholm describes as the first mark of intentionality, the power to say that so-and-so is the case when so-and-so is not the case, the power to misrepresent how things stand in the world. Unlike compasses, these fancy items are not to be found on the shelves of hardware stores.”

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misrepresentation • when the compass is used correctly (in

particular, with no magnetic interfence), theneedle will always point north

• that is, without interference, if the needle points in direction d, then d is the direction of the north pole

• this fact is does not depend on the purposesand attitudes of the designers and users of compasses

• this is the sense in which the compass hasunderived/original intentionality: withoutinterference, it infallibly indicates the directionof the north pole 6

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misrepresentation • interference is possible: a tv set might cause

the needle to point east • in this situation, the compass misrepresents

the location of the north pole • but: the compass only misrepresents the

location of the north pole because of “thepurposes and attitudes of its designers”

• so the compass doesn’t help us understandhow a physical system could exhibit the “firstmark of intentionality”—the power tomisrepresent

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natural functions

• “if an information-carrying element in asystem could somehow acquire the functionof carrying information, and acquire thisfunction in a way that did not depend on ourintentions, purposes, and attitudes, then itwould thereby acquire…the power tomisrepresent the conditions it had thefunction of informing about”

• two possible ways of acquiring suchfunctions: phylogenic, ontogenic

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phylogenic

• “If the heart has the function of pumpingblood…then…the senses…might have aninformation processing function…Therewould thus exist, inside the animal, representations of its environment, elementscapable of saying something false”

• but this could not explain how an animalmight acquire representations of itsenvironment through learning

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ontogenic

• assume the system has a need for theinformation that p (e.g. that there is a poisonousthing nearby)

• assume it has an internal state S that indicates that p

• add a natural process, one capable of conferringon S the function of indicating that p

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ontogenic

• “…the result will be a system with internalresources for representing (with the associatedpower of misrepresenting) its surroundings.Furthermore, that this system represents, aswell as what it represents, will be independentof what we know or believe about it…The entire process can happen spontaneously and, when itdoes, the system will have its own cache oforiginal intentionality.”

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ontogenic

• but is this a recipe for thought? • “To acquire the function of indicating F, to become

(thereby) a representation of F…a structure must play apart in the production of behavior that is rational from thepoint of view of the organism’s well-being.”

• had the structure indicated G, “a condition unrelated to a useful outcome, [it] would not have been selected forproducing a response to F.”

• “Rationality emerges as a by-product in the very processin which representations are created.”

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limitations and problems • not clear how to extend the story to thoughts (beliefs)

that do not concern environmental conditions relevant to the organism’s survival (e.g. that Dretske’s paperis interesting)

• not clear how to extend the story to other sorts ofintentional states (intentions, wants, hopes, etc.)

• why would a poison-representing internal state havethe function of indicating that there’s somethingpoisonous nearby?

• supposing that not all red things are poisonous, mightnot the state’s function be to indicate that a red thingis nearby? (false positives don’t matter much; false negatives are to be avoided at all costs)

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a different approach: “True believers”

•

•

• Daniel Dennett

Dretske gives areductive account of thought—an accountthat does not help itselfto any mentalingredients Dennett, like Dretske, wants to show how a merely physical systemcould have thoughts but Dennett’s account is nonreductive—it does use mental ingredients14

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three predictive strategies

• the physical stance • the design stance • the intentional stance

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the physical stance

• use the system’s physical properties and the laws of physics to predict its behavior

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the design stance

• assume that the system isdesigned to do such-and-such,and predict its behavior on thisbasis

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the intentional stance

• treat the system as a rational agent, figure outwhat beliefs and desires it ought to have,given its place in the world

“A little practical reasoningfrom the chosen set of beliefs and desires will in many—butnot all—instances yield adecision about what the agentought to do; that is what youpredict the agent will do” (558)

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the power of the intentional stance

• “a fact largely concealed by our typical concentrationon the cases in which it yields dubious or unreliableresults”

• the prediction contest: Martian super-physicists vs.Earthlings

where will you be in exactly one week?

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the “perverse claim”

• “all there is to being a true believer is being asystem whose behavior is reliably predictablevia the intentional strategy, and hence all there is to really and truly believing…p (forany proposition p) is being an intentionalsystem for which p occurs as a belief in the best (most predictive) interpretation”

• this is a “nonreductive” account of believing pbecause ‘being an intentional system forwhich…’ contains mental vocabulary

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Minds and Machines spring 2003

• read Davidson, Kim

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